1. Field of the Invention
The present invention relates to water-soluble natural film and its preparing method. More particularly, the present invention relates to water-soluble natural film manufactured by dissolving as an active ingredient a water-soluble chitosan prepared in such a manner that chitin/chitosan decomposed with lysozyme is rinsed with ethanol, subjected to electric adjustment and sonication in a saline solution and to ion-exchange to obtain water-soluble β-glucosamine fibrin followed by nano-sized coating the β-glucosamine fibrin with immunoglobulin (γ-globulin), and seaweeds and functional ingredients in distilled water and gelatinating.
2. Description of the Related Art
Chitosan is an aminopolysaccharide present in nature, which is typically obtained by deacetylation of chitin found in shells of crab and shrimp, cuttlebones, and cell walls of fungi, mushrooms and bacteria. Chitosan exhibits nontoxic, biodegradable and biocompatible. In addition, chitosan is useful in tissue culture and has antibiotic activity and hemostatic activity. Furthermore, chitosan has been known to show a variety of physiological functions such as reduction of cholesterol level, promotion of metabolism in intestine, anticancer activity via enhancing immunity, improvement of liver function, reduction of glucose level in blood and detoxification of heavy metals.
Chitin exhibits strong resistance to chemical reagents and insolubility in water and organic solvents via strong intramolecular hydrogen bonds due to the presence of acetylamino groups in the molecule. Such properties make it difficult to process chitin for the formation fiber and film and therefore act as an obstacle against active application of chitin. Therefore, various attempts have been made to obtain water-soluble chitosan with excellent physical properties compared to chitin. Chitin has been typically converted via its deacetylation to chitosan that exhibits water solubility in aqueous phase with weak acidity.
Chitin and chitosan have been primarily used as a flocculant for recovering active ingredients in waste water generated by food plants. Recently, they have been improved by modification and thus extended their applications to a wide variety of fields including food, medicines, functional membranes, biotechnology, cosmetics, agriculture, chemical engineering and environment. Meanwhile, a high quality and functional chitin or chitosan useful in clinical medicine widens its fields of application; however, the conventional methods developed so far fail to meet the requirements for preparing chitin or chitosan that exhibits higher functionality and applicability to various clinical medicines.
Various techniques have been proposed to process chitin or chitosan for the formation of film or fiber:
U.S. Pat. No. 3,533,940 discloses that chitosan prepared from chitin is dissolved in aqueous organic acid solution such acid acetic acid to form a solution for forming fiber or film. In addition, U.S. Pat. No. 4,699,135 teaches (a) a method for preparing chitin fiber performed by dissolving chitin in a polar organic solvent such as dimethylacetamide containing lithium chloride and (b) a chitosan monofiber obtained from chitosan dissolved in an aqueous solution of acetic acid.
U.S. Pat. No. 4,996,307 discloses a method for preparing water-soluble acylated chitosan with high molecular weight having a degree of acylation of 35–65, in which the acylated chitosan may be obtained in high yield within a few hours in the same system. Further, U.S. Pat. No. 5,900,479 discloses a method for preparing water-insoluble chitinous film or fiber by use of a chitosan solution that is obtained by dissolving chitin in an aqueous organic acid solution.
However, the final products made of the films and fibers prepared by the methods described above are solution containing organic acid or have dissolved form in organic acid, so that the films and fibers with no water solubility show limited applicability.